public BTNode(string name, double value)
{
Name = name;
Value = value;
Left = null;
Right = null;
}
public void delete(string key)
{
BTNode parent = null;
// First find the node to delete and its parent
BTNode nodeToDelete = findParent(key, ref parent);
if (nodeToDelete == null)
throw new Exception("Unable to delete node: " + key.ToString()); // can't find node, then say so
// Three cases to consider, leaf, one child, two children
// If it is a simple leaf then just null what the parent is pointing to
if ((nodeToDelete.Left == null) && (nodeToDelete.Right == null))
{
if (parent == null)
{
root = null;
return;
}
// find out whether left or right is associated
// with the parent and null as appropriate
if (parent.Left == nodeToDelete)
parent.Left = null;
else
parent.Right = null;
_count--;
return;
}
// One of the children is null, in this case
// delete the node and move child up
if (nodeToDelete.Left == null)
{
// Special case if we're at the root
if (parent == null)
{
root = nodeToDelete.Right;
return;
}
// Identify the child and point the parent at the child
if (parent.Left == nodeToDelete)
parent.Right = nodeToDelete.Right;
else
parent.Left = nodeToDelete.Right;
nodeToDelete = null; // Clean up the deleted node
_count--;
return;
}
// One of the children is null, in this case
// delete the node and move child up
if (nodeToDelete.Right == null)
{
// Special case if we're at the root
if (parent == null)
{
root = nodeToDelete.Left;
return;
}
// Identify the child and point the parent at the child
if (parent.Left == nodeToDelete)
parent.Left = nodeToDelete.Left;
else
parent.Right = nodeToDelete.Left;
nodeToDelete = null; // Clean up the deleted node
_count--;
return;
}
// Both children have nodes, therefore find the successor,
// replace deleted node with successor and remove successor
// The parent argument becomes the parent of the successor
BTNode successor = findSuccessor(nodeToDelete, ref parent);
// Make a copy of the successor node
BTNode tmp = new BTNode(successor.Name, successor.Value);
// Find out which side the successor parent is pointing to the
// successor and remove the successor
if (parent.Left == successor)
parent.Left = null;
else
parent.Right = null;
// Copy over the successor values to the deleted node position
nodeToDelete.Name = tmp.Name;
nodeToDelete.Value = tmp.Value;
_count--;
}
private BTNode findParent(string name, ref BTNode parent)
{
BTNode np = root;
parent = null;
int cmp;
while (np != null)
{
cmp = String.Compare(name, np.Name);
if (cmp == 0) // found !
return np;
if (cmp < 0)
{
parent = np;
np = np.Left;
}
else
{
parent = np;
np = np.Right;
}
}
return null; // Return null to indicate failure to find name
}
private void killTree(ref BTNode p)
{
if (p != null)
{
killTree(ref p.Left);
killTree(ref p.Right);
p = null;
}
}
private void add(BTNode node, ref BTNode tree)
{
if (tree == null)
tree = node;
else
{
// If we find a node with the same name then it's
// a duplicate and we can't continue
int comparison = String.Compare(node.Name, tree.Name);
if (comparison == 0)
throw new Exception();
if (comparison < 0)
{
add(node, ref tree.Left);
}
else
{
add(node, ref tree.Right);
}
}
}
// Simple 'drawing' routines
private string drawNode(BTNode node)
{
if (node == null)
return "empty";
if ((node.Left == null) && (node.Right == null))
return node.Name;
if ((node.Left != null) && (node.Right == null))
return node.Name + "(" + drawNode(node.Left) + ", _)";
if ((node.Right != null) && (node.Left == null))
return node.Name + "(_, " + drawNode(node.Right) + ")";
return node.Name + "(" + drawNode(node.Left) + ", " + drawNode(node.Right) + ")";
}
public BinaryTree()
{
root = null;
_count = 0;
}
public BTNode insert(string name, double d)
{
BTNode node = new BTNode(name, d);
try
{
if (root == null)
root = node;
else
add(node, ref root);
_count++;
return node;
}
catch (Exception)
{
return null;
}
}
public BTNode findSuccessor(BTNode startNode, ref BTNode parent)
{
parent = startNode;
// Look for the left-most node on the right side
startNode = startNode.Right;
while (startNode.Left != null)
{
parent = startNode;
startNode = startNode.Left;
}
return startNode;
}
public BinaryTree()
{
root = null;
_count = 0;
}
public void delete(string key)
{
BTNode parent = null;
// First find the node to delete and its parent
BTNode nodeToDelete = findParent(key, ref parent);
if (nodeToDelete == null)
{
throw new Exception("Unable to delete node: " + key.ToString()); // can't find node, then say so
}
// Three cases to consider, leaf, one child, two children
// If it is a simple leaf then just null what the parent is pointing to
if ((nodeToDelete.Left == null) && (nodeToDelete.Right == null))
{
if (parent == null)
{
root = null;
return;
}
// find out whether left or right is associated
// with the parent and null as appropriate
if (parent.Left == nodeToDelete)
{
parent.Left = null;
}
else
{
parent.Right = null;
}
_count--;
return;
}
// One of the children is null, in this case
// delete the node and move child up
if (nodeToDelete.Left == null)
{
// Special case if we're at the root
if (parent == null)
{
root = nodeToDelete.Right;
return;
}
// Identify the child and point the parent at the child
if (parent.Left == nodeToDelete)
{
parent.Right = nodeToDelete.Right;
}
else
{
parent.Left = nodeToDelete.Right;
}
nodeToDelete = null; // Clean up the deleted node
_count--;
return;
}
// One of the children is null, in this case
// delete the node and move child up
if (nodeToDelete.Right == null)
{
// Special case if we're at the root
if (parent == null)
{
root = nodeToDelete.Left;
return;
}
// Identify the child and point the parent at the child
if (parent.Left == nodeToDelete)
{
parent.Left = nodeToDelete.Left;
}
else
{
parent.Right = nodeToDelete.Left;
}
nodeToDelete = null; // Clean up the deleted node
_count--;
return;
}
// Both children have nodes, therefore find the successor,
// replace deleted node with successor and remove successor
// The parent argument becomes the parent of the successor
BTNode successor = findSuccessor(nodeToDelete, ref parent);
// Make a copy of the successor node
BTNode tmp = new BTNode(successor.Name, successor.Value);
// Find out which side the successor parent is pointing to the
// successor and remove the successor
if (parent.Left == successor)
{
parent.Left = null;
}
else
{
parent.Right = null;
}
// Copy over the successor values to the deleted node position
nodeToDelete.Name = tmp.Name;
nodeToDelete.Value = tmp.Value;
_count--;
}